A number of publications are cited herein in order to more fully describe and disclose the invention and the state of the art to which the invention pertains. Each of these references is incorporated herein by reference in its entirety into the present disclosure, to the same extent as if each individual reference was specifically and individually indicated to be incorporated by reference.
Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise,” and variations such as “comprises” and “comprising,” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a pharmaceutical carrier” includes mixtures of two or more such carriers, and the like.
Ranges are often expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment.
This disclosure includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Glucocorticoids (cortisol in man, corticosterone in rodents) are hormones that regulate a range of pathways involved in stress and metabolic signalling. They are antagonists of insulin action and impair insulin-dependent glucose uptake, increase lipolysis, and enhance hepatic gluconeogenesis. These effects are evident in Cushing's syndrome, which is caused by elevated circulating levels of glucocorticoids. The features of Cushing's syndrome are diverse and reflect the tissue distribution of glucocorticoid receptors in the body. They include a cluster of metabolic (central/visceral obesity, insulin resistance, hyperglycaemia, dyslipidaemia) and cardiovascular (hypertension) abnormalities which, when observed in patients without Cushing's syndrome, constitute the metabolic syndrome. These abnormalities confer a substantial risk of cardiovascular disease. In addition, Cushing's syndrome is associated with neuropsychiatric manifestations including depression and cognitive impairment. The features of Cushing's syndrome are reversible upon removal of the cause of glucocorticoid excess.
It is recognised that glucocorticoid activity is controlled at the tissue level by the intracellular conversion of active cortisol and inactive cortisone by 11β-hydroxysteroid dehydrogenases (see, e.g., Seckl et al., 2001). These enzymes exist in two distinct isoforms. 11β-HSD1, which catalyses the reaction that activates cortisone, is expressed in liver, adipose tissue, brain, skeletal muscle, vascular smooth muscle and other organs, while, 11β-HSD2, which inactivates cortisol, is predominantly expressed in the kidney. Pharmacological inhibition of 11β-HSD1 in rat and man with carbenoxolone (see, e.g., Walker et al., 1995), and transgenic knockout in mice (see, e.g., Kotelevtsev et al., 1997), results in enhanced hepatic insulin sensitivity and reduced gluconeogenesis and glycogenolysis, suggesting that 11β-HSD1 inhibition will be a useful treatment in type 2 diabetes and other insulin resistance syndromes. Furthermore, mice lacking 11β-HSD1 possess low triglycerides, increased HDL cholesterol, and increased apo-lipoprotein A-I levels (see, e.g., Morton et al., 2001), suggesting that inhibitors of 110-HSD1 may be of utility in the treatment of atherosclerosis.
The link between 11β-HSD1 and the metabolic syndrome has been strengthened by studies in transgenic mice and man. 11β-HSD1 knockout mice on two different genetic backgrounds are protected from dietary obesity (see, e.g., Morton et al., 2004), while administration of carbenoxolone to patients with type 2 diabetes enhances insulin sensitivity (see, e.g., Andrews et al., 2003). However, it has become apparent that the key tissue in which 11β-HSD1 exerts the greatest influence upon metabolic disease is the adipose tissue rather than the liver. Mice with transgenic overexpression of 11β-HSD1 in adipose tissue (see, e.g. Masuzaki et al., 2001) have a more profound metabolic syndrome and obesity than mice with overexpression in liver (see, e.g., Paterson et al., 2004). In obese humans, 11β-HSD1 activity is increased in adipose tissue, but enzyme activity is decreased in the liver (see, e.g., Rask et al., 2001).
In the CNS, 11β-HSD1 is highly expressed in regions important for cognition such as hippocampus, frontal cortex, and cerebellum (see, e.g., Moisan et al., 1990). Elevated cortisol is associated with cognitive dysfunction, and glucocorticoids have a range of neurotoxic effects. 11β-HSD1 knockout mice are protected against age-related cognitive dysfunction (see, e.g., Yau et al., 2001), while administration of the 11β-HSD inhibitor carbenoxolone has been shown to enhance cognitive function in elderly men and type 2 diabetics who have a selective impairment in verbal memory (see, e.g., Sandeep et al., 2004). Thus, 11β-HSD1 inhibitors are of potential therapeutic utility in the treatment of diseases such as Alzheimer's Disease, which are characterised by cognitive impairment.
The isozymes of 11β-HSD are also expressed in the blood vessel wall (see, e.g., Walker et al., 1991; Christy et al., 2003). 11β-HSD1 is expressed in vascular smooth muscle, while 11β-HSD2 is expressed in endothelial cells where it modulates endothelial-dependent vasodilation (see, e.g., Hadoke et al., 2001). 11β-HSD1 knockout mice have normal vascular function, but they exhibit enhanced angiogenesis in response to inflammation or ischaemia (see, e.g., Small et al., 2005). This offers therapeutic potential in the treatment of myocardial infarction, since inhibition of 11β-HSD1 may enhance revascularisation of ischaemic tissues.
Studies have shown that 11β-HSD1 affects intraocular pressure in man (see, e.g., Rauz et al., 2001). Inhibition of 11β-HSD1 may be useful in reducing intraocular pressure in the treatment of glaucoma.
Glucocorticoids are involved in the regulation of bone formation and skeletal development. Treatment of healthy volunteers with carbenoxolone led to a decrease in bone resorption markers suggesting that 11β-HSD1 plays a role in bone resorption (see, e.g., Cooper et al., 2000). 11β-HSD1 inhibitors could be used as protective agents in the treatment of osteoporosis.
The inventors have discovered compounds that inhibit 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) that are useful in the treatment, control, and/or prevention of disorders (e.g., diseases) that are responsive to the inhibition of 11β-HSD1.